Gastrointestinal tract ulcer, gastritis, and reflux esophagitis are generated while the balance between offensive factors (for example, gastric acid, Helicobacter bacteria pepsin, stress, alcohol and tobacco, etc.) and defensive factors (for example, gastric mucosa, bicarbonate, prostaglandin, the degree of blood supply, etc.) is destroyed. Therefore, a therapeutic agent for treating gastrointestinal damage such as gastrointestinal tract ulcer, gastritis and reflux esophagitis is divided into a drug for inhibiting the offensive factors and a drug for enhancing the defensive factors. As the drug for inhibiting the offensive factors, an antacid, an anticholinergic drug, a H2 receptor antagonist, a proton pump inhibitor (PPI), an acid pump antagonist (APA) also referred to as a reversible proton pump inhibitor, and the like have been known. For example, as drugs having gastric acid pump antagonistic activity, WO2006/025716 discloses pyrrolo[2,3-c]pyridine derivatives, and WO2007/072146 discloses benzimidazole derivatives. In addition, WO2006/036024 discloses pyrrole derivatives having a reversible proton pump inhibitory activity.
On the other hand, it is reported that gastrointestinal tract ulcer, gastritis, and reflux esophagitis occur ulcers even without an increase in secretion of gastric acid. Thus, as much as the offensive factor increases, a reduction in the defensive factor due to a pathological change of the gastric mucosa is thought to play an important role in the occurrence of gastric ulcers. Thus, in addition to drugs for inhibiting the offensive factors, drugs for enhancing the defensive factors are used for the treatment of gastrointestinal tract ulcer and gastritis. As the drugs for enhancing the defensive factors, mucosal protective drugs which are attached to the ulcer site to form a physicochemical membrane, and drugs that promote the synthesis and secretion of mucus have been known.
On the other hand, Helicobacter pylori (H. pylori), which is a bacteria present in the stomach, has been known to cause chronic gastritis, gastric ulcer, duodenal ulcer and the like, and a large number of patients with gastrointestinal damages are infected with H. pylori. Therefore, these patients must take antibiotics such as clarithromycin, amoxicillin, metronidazole, tetracycline, together with anti-ulcer agents such as a proton pump inhibitor, or an acid pump antagonist. Consequently, various side effects have been reported.
Therefore, there is a need to develop anti-ulcer drugs which inhibit the secretion of gastric acid (for example, proton pump inhibitory activity) and enhance defensive factors (for example, an increase in mucus secretion) and at the same time have eradication activity against H. pylori. 
Further, studies for G-protein coupled receptor (GPCR) that can cause several diseases have also been performed.
Specifically, 5-hydroxytryptamine (5-HT, serotonin) is an effective factor of gastrointestinal tract, a regulator of platelet and a neurotransmitter of central nervous system, derived from tryptophan, and it can influence on almost all physiological and behavioral functions such as emotion, appetite, cognition, vomiting, endocrine system function, digestive system function, motor function, neurotrophic, perception, sensation function, sex, sleep and cardiovascular function.
Like this, 5-HT is involved in various functions, and the reason has been known to be due to 5-HT cell bodies that are clustered in the brainstem raphe nuclei, an anatomical structure of serotonergic system having a huge neurite that influence on all area of central nervous system neuraxis, a molecular diversity of various 5-HT receptor subtypes present in the cell membrane, and a characteristic cytological distribution (Mohammad-Zadeh, L. F.; Moses, L.; Gwaltney-Brant, S. Serotonin: a review. J. Vet. Pharmacol. Therap. (2008) 31, 187-199, Glennon, R. A.; Dukat, M.; Westkaemper, R. B. Psychopharmacology—The Fourth Generation of Progress).
These 5-HT receptors are classified into seven families (5-HT1 to 5-HT7) including 14 receptor subtypes, depending on the structural, functional and pharmacological standards, among which, except for 5-HT3 receptor which is the opening/closing passage of ligand, all of the receptors correspond to GPCR. In particular, 5-HT2 receptors are classified into 5-HT2A, 5-HT2B, and 5-HT2C receptors, and all of these receptors increase the production of inositol 1,4,5-triphosphate (IP3) by activating phospholipase C (PLC). Thus, recently, most of the drugs that are used for the treatment of psychiatric disorders (for example, depression, manic depression, schizophrenia, autism, obsessive-compulsive neurosis, anxiety disorder, etc.) have been known to act through the serotonergic mechanism. Further, it is reported that diseases such as migraine, hypertension, eating disorders, and irritable bowel syndrome (IBS) are also associated with 5-HT.
On the other hand, acetylcholine is a neurotransmitter of autonomic nervous system and acts on both the central nervous system and the peripheral nervous system, thereby affecting brain and muscular system. Such acetylcholine receptor can be divided into nicotinic acetylcholine receptor (nAChR) as an ionic receptor and a muscarinic acetylcholine receptor (mAChR) as a metabolite receptor. Among them, the muscarinic acetylcholine receptor (mAChR) was identified to include five distinct receptor subtypes, each of which are referred to as M1 to M5 receptors, and these also correspond to GPCR.
In particular, M1 receptors are present in the cerebral cortex of the hippocampus, and involved in the autonomic nerve, salivary gland, gastric secretion and the like. M2 receptors are present in heart, brain cortex and hippocampus, and involved in a decrease of heart rate, a reduction of atrial contraction force, a decrease in the conduction velocity of AV node, and the like. Specifically, when exposed to acetylcholine for up to few seconds, the cortex pyramidal neurons are inhibited through M1 muscarinic receptor linked to an alpha subunit of Gq-type G proteins. Therefore, when the M1 receptor is activated, the calcium stored in the cell is released to occur potassium conduction activated by the release of calcium, thereby the spiking of pyramidal neurons can be inhibited.
By inhibiting the action of these M1 and M2 receptors, various diseases can be prevented or treated. Specifically, as the therapeutic agents for inhibiting the action of M1 receptors, a therapeutic agent for the treatment of a peptic ulcer such as pirenzepine using the effects of preventing the secretion of gastric acid and reducing the stomach cramps, a therapeutic agent for the treatment of diabetic neuropathy using the effect of reducing a nerve conduction velocity and preventing a tactile allodynia and thermal hypoalgesia, and the like have been known. As the therapeutic agents for inhibiting the action of M2 receptors, a therapeutic agent for the treatment of overactive bladder using the effects of inhibiting allergic reactions induced by M2 receptors, a therapeutic agent for the treatment of asthma, and the like have been known. Therefore, it appears that the muscarinic acetylcholine antagonist is likely to be developed as a therapeutic agent for the treatment of diseases such as peptic ulcer, diabetic neuropathy, asthma, and overactive bladder.
Consequently, in order to prevent and treat diseases associated with 5-HT and acetylcholine, it is necessary to study compounds which can exhibit an inhibitory action on their GPCR, particularly 5-HT2A, M1 and M2 muscarinic receptors.
Given the above circumstances, the present inventors have conducted numerous studies and found that 4-methoxy pyrrole derivatives or pharmaceutically acceptable salts thereof have excellent anti-ulcer activity (i.e., proton pump inhibitory activity, etc.) and eradication activity against H. pylori and thus are useful in the prevention and treatment of gastrointestinal damage due to gastrointestinal tract ulcer, gastritis, reflux esophagitis or H. pylori. In addition, the present inventors have found that these 4-methoxy pyrrole derivatives or pharmaceutically acceptable salts thereof have inhibitory activities against GPCRs that cause diseases, for example, 5-HT2A, M1 and M2 muscarinic receptors and the like, and thus can be effectively used for the prevention and treatment of 5-HT receptor or muscarinic acetylcholine receptor-mediated diseases. The present invention has been completed on the basis of such a finding.